Light ends recovery in fluid hydroforming



mbuoh. mm

6 r l wuj :YI o 8 9, .m ma n |.v W. I 7 o 2 www rl:o 3 J U.

ulON. r..

m mw 20?@0004 Tu M Al m NH Iv \llm2ON. @Q JOOU mw m20 FFW ME.. HN.. nu T IdOlNOQOI 9 waommu u ON AI 1, @2460 OH 10F E|=0ml N U( Ouml A 23 om w d. r mnoN. :QFMW u 02oomml O Bm,

LIGHT ENDS RECOVERY IN FLUID HYDROFORMING Wilson C. Rich, Jr., Mountainside,

Esso Research and tion of Delaware I Application July 29, 1952, Serial No. 301,563

N. assignor to Engineering Company, a corpora- The present invention is concerned with an improved hydroforming operation. The invention is more particularly concerned with a process of segregating and recovering hydrocarbon constituents boiling in the motor fuel boiling range secured from a hydroforming operation. In accordance with the presentV invention, the product gases from the hydrofonner containing relatively large volumes of hydrogen are processed in an integrated separation zone, absorption zone and stabilization zone wherein considerably less quantities of lean oil circulation are required in order to secure equivalent recovery of desired hydrocarbon constituents boiling in the motor fuel boiling range.

Itis well known in the art to treat various hydrocarbon fractions under conditions that hydrogen is formed. For instance, it is known to treat petroleum fractions boiling below about 430 F. at temperatures in therange from about 800 F. to 1000 F., and at pressures in the range from about to 300 lbs. per inch in the presenceof a catalyst such as molybdenum oxide onalumina under conditions to dehydrogenate the molecule and tosecure a resultant product of improved'- octane number.' It is also known in the art to carry out various oil absorption operations wherein desired hydrocarbon constituents are absorbed in the oil and later recovered from the oil. Unv desirable hydrocarbon constituents passvoverhead from the absorption zone. The processing of the gases, such as those secured from a hydroforming operation which contains relatively large volumes of hydrogen in order to segregate the desired hydrocarbon constituents heretofore have presented several problems. In korder to secure eicient absorption and separation of the desired hydrocarbon constituents from the gases, relatively large volumes of absorption oil have been required. In accordance with the present process, the quantity of the yrequired oil in the absorption zone is materially lessened by' introducing uncondensed gases from Aa separation zone into an intermediate point of the oil absorption zone and iritroducing stabilizer gases from a stabilization zone which are substantially free of hydrogen into the bottom of the absorption zone. i

The process of the present invention may be more fully understood by reference to the drawing illustrating one embodiment of the same. Referring specifically *tol the drawing, a hydrocarbon feed fraction, as for example`,ione boiling in the range from about 100 F. to 430 F. is. introduced into hydroforming zone 2 by means of line 1. Temperatures in zone 2 are in the range from about 85 0 F. to 950 F. while the pressure is about 200 lbs. per sq. in. gauge. The catalyst may comprise any suitable hy-v droforming catalyst, as for example 10% molybdenum oxide on alumina carrier. The product gases from the hydroforming zone comprising relatively large^volumes of hydrogen are removed by means offline `3, passed through a cooling zone 4 and introduced into separation zone 5. A typical analysis of a hydroforming 'product including recycle gas is as follows:

ICC

. Mol Percent Hydrogen 57 Methane `12 Ethane and C2 unsaturates 8 Propane and C3 unsaturates 5 Butanes and C4 unsaturates 3 Pentanes and C5 unsaturates and hydrocarbons containing more than liveV carbon atoms per, moleculek `1,5

Uncondensed gases, zone 2 are removed overhead from separation zone 5 by means of line 6. A typical analysis of theseuncondensed gases is for example:

Hydrogen 67 Methane 15 Ethane and C2 unsaturates 8 Propane and C3 unsaturates; 5 Butanes and C4 unsaturates f 3 Pentanes and C5 unsaturates andhydrocarbons containing more than ve carbon atomsper molecule 2v The liquid condensate product, a typical-'analysis of which is as follows:

Pentanes and C5 unsaturates and hydrocarbons contalning more than five carbon atoms per n 100.0 is withdrawn from the'bottom of zone S by means of line 7 and introduced into a stabilization zone 8. Temperature and pressure conditions in zone 8 are adapted to remove overhead hydrocarbon constituents boiling below hydrocarbons containing five carbon atoms inthe molecule. This stream is removed overhead by means of lline 9, cooled in cooling zone 10 and passed into separation zone 11. A typical analysisv of the stream' removed by means of line 9is asl follows: f

Hydrogen 2.5 Methane 2O Ethane and C72 unsaturates v36.5 Propane and C3 unsaturates 22 Butanes and C4 unsaturates 19 The temperature in the bottom of stabilization zone 8 is in the rangefrom about 500 F. to 600 F., while theA ktop temperature is in `the range from about F.,to 20 F. A liquid product streamis withdrawn from secondary separation i i typical analysis ofthis :stream is as follows:

a portion of which are recycled to Mol Percent Mol Percent zone 11 by means of l,line 12. A

A bottoms stream is removed from stabilization zone 8 by means of line 13; A typical analysis is as follows:

L. V. Percent Hydroformed Hydrocarbons boiling in motor fuel range"" u- 5l Absorption oil 49.

This streamis introduced into a distillation zone 14 whereina separation is made between the hydroformed hydrocarbon ('hydroformate) and lean oil.' `Distillation zone 14 is operated at substantially atmospheric pressure. The bottoms temperature is in the range from about 375 to 500i E., preferably in thel rangefrom about400' F. to 45,0-" F., while thev top temperature, is in theY rangel from aboutOOf Rito 375 F. A liquidstabilizedl low boiling hydroformate product is removed overhead from the distillation zone through line 1S, condensed and further refined as desired.

A heavy hydroformate boilinginthe range from about 325 F. to 43Q F. is removed` by means of line 16. At least a portion of this stream is recycled to the top of an absorptionzone 17 by means of line 18, while` the remainder is withdrawn from the system andV further rened and` handled as desired.

.An uncondensed stream is withdrawn from the top of separation zone 11 byV means of line 20. A typical analysisof this stream is as follows: Y

' Mol Percent Hydrogen 13.6 Methane l0.6 Ethane and C2 unsaturates 35 .0 Propane andV C3 unsaturates 27 Butanes and C4 unsaturates 13.8

In accordance with the present invention, the, net portion of the hydrogen-rich gas made in the'hydroforming reaction withdrawn from the top of separation zone 5 is introduced into an intermediate point of absorption zone 1f7- by means of line 19. Also, in accordance with the present invention, the vaporous stream withdrawn from the top of zone 11 by means of line 20 ispassed into the bottom of absorption zone 17.

l'I heprocess of the present invention generally covers an improved method of handling hydrogen-rich gas` secured from a hydroforming operation. In hydroforming operations, the large quantities of hydrogen produced tend to carry appreciable quantities of valuable materials such as butanes and heavier components into the vapor stream. However, in accordance with the present invention, the stabilizer gas is`processed in the lower areafo an absorber. l

Inthe upper section of the absorption tower, the, high concentration of hydrogen has the eiect of lowering the eiective absorption pressure. Thus, when the lean oil plus absorption naphtha leaves the upper section and enters the lower section where a low partial pressure of hydrogen exists, the, liquid still has appreciable absorption capacity and, because of the high ratio of. liquid to gas in the lower section, can etect essentially complete4 absorption of the C3 and C4 portions contained in ther gas feed to this lower section fromvthe stabilizerv through.

line 20. Thus, the recoverable portions of the gas fromthe stabilizer are not sent to the main section of the absorber and do not require additional lean oil for their recovery.

The process of the present invention maybemorefully understood by the following example; illustrating they same.

I'xarrtpvle,A

Inan operation wherein the analysis of the gases from the initial separation zone, the secondary separation zone, and the gas from the absorption zone were as follows:

Initial Secondary From Separation Separation Absorption Zone Line Zone Line Zone Line 19 20 21 Mols Mols Mols Water 6 6 668 8. 4 672 144 6. 5 146' 84 21. 5 79 Propane and C3 unsaturates 52 16.7` A 40 Butanes and G4 unsaturates 28 8.3 10. 5 Pentanes and O5 unsaturates and hydrocarbons containing more than five carbon atoms per molecule 1S 0. 1

Total--. 1, 000 61.5 953. 5

and. wherein in one operation the gas fromlineslQ-'and 20; were combined and introduced into said absorption zone, andwherein in av secondv operationthe gas'from'thel secondary separation zone was passed intothe lower area of said absorption zone and the. gas from thev said initialy zone was passed into an intermediate point of said absorp-` tion zone. The amount of leanV oil required for 71%? of butane recovery was as follows:

Lean oil requirements for 71% C4 recovery Operation I 245 B/ 1000 mols` gas Operation II 200 B/ 1000 mols gas results in that the amount of oil. circulatedis materially.`

reduced.

What is claimed is:

l. Improved processfor thesegregation of hydrocar b ons; boiling in the motor fuelv boiling. range from a vaporous mixture containing saidV hydrocarbons, lower boiling hydrocarbons and a predominantly large mol per.- cent of hydrogen which comprises segregating a vaporous stream comprising saidllower boiling hydrocarbons, some of said` hydrocarbons boiling in the motor fuel boiling range and the hydrogen fromV a condensedy hydrocarbon stream substantially completely free of hydrogen in an initial separation zone, passing said condensed stream' toaz stabilization zone wherein a separationk is madebetween hydrocarbons boiling in. theV motor fuel boiling` range andvlower boilingV hydrocarbons, passingsaid' hy' drocarbons boiling in the motor fuel boiling range to a# i distillation zone wherein a separation is. made between.'

low boiling hydrocarbons and high boiling,hydrocarbons',4

passing atleast a portion; of said high boiling hydrocar bons from said distillation zone intoV the top, of an abf'` sorption zone as an absorptionV oil, removing. overhead from said stabilization zone lower boiling hydrocarbons,

cooling the same and passing the cooled. stream. to;` a secondary separation zone, segregating uncondensed hydrocarbons andl passingA the same to a lowerY pointk of` said absorption zone, passing said vaporous stream from,

said initial separation zone into. antintermediate point of said absorption zone, countercurrently contacting the upowing vaporous stream with said downowing absorp: tion oil, whereby said hydrocarbons boilingin the motor fuel boiling range are absorbed in said absorption oil, removing hydrogen and hydrocarbons boiling below the, motor fuel boiling range overhead from said absorption zone and removing said absorption oil comprising said higher boiling hydrocarbons and absorbed hydrocarbons from the bottom of said absorption zone and'passingthe same to said stabilization zone.

2. Process as defined by claim l, wherein said vaporousVV hydrocarbon mixture is secured'. from a hydi'oforming-Y process.

3. Improved integrated operation comprising a hydroforming step and a light end recovery step which comprises hydroforming a petroleum fraction boiling in the motor fuel boiling range at a temperature in the range from about 850 F. to 950 F., and at a pressure of about 200 lbs. in the presence of a dehydrogenation catalyst, removing the hydroformed product and cooling the same, passing the cooled product into an initial separation zone, segregating a gaseous product in said initial separation zone, which gaseous product is characterized by containing a predominantly large mol percent of hydrogen, introducing said gaseous product at an intermediate point into an absorption zone, removing from initial separation zone a condensate, introducing said condensate into a stabilization zone, maintaining conditions in said stabilization zone to remove overhead as a vapor hydrocarbon constituents containing 4 and less carbon atoms in the molecule, cooling said vapors and introducing the cooled vapors into a secondary separation zone, removing vapors from said secondary separation zone and introducing said latter vapors into said absorption zone at a point below the point of introduction of said vapors from said initial separation zone, withdrawing as bottoms from said stabilization zone a hydroformed product boiling in the range extending from the boiling range of hydrocarbons having 5 carbon atoms in the molecule up to 430 F., introducing said latter product into a distillation zone, maintaining conditions in said distillation zone to remove overhead a reformate boiling in the range between about 100 F. and 325 F., removing as a bottoms product from said distillation zone a heavy reformate` boiling in the range from about 325 F. to 430 F., introducing at least a portion of said heavy reformate into the top of said absorption zone, countercurrently contacting said vapors from said initial separation zone and said vapors from said secondary separation zone with said heavy reformate in said absorption zone, maintaining conditions in said absorption zone to absorb in said heavy reformate hydrocarbons containing 4 and more carbon atoms in the molecule, withdrawing from said absorption zone said heavy reformate containing said absorbed hydrocarbons and passing the same to said stabilization zone along with said condensate from said initial separation zone.

References Cited in the le of this patent UNITED STATES PATENTS 2,181,302 Keith Nov. 29, 1939 2,184,096 Gerhold Dec. 19, 1939 2,327,187 Hill` Aug. 17, 1943 2,388,732 Finsterbusch Nov. 13, 1945 2,404,902 Claussen et al. July 30, 1946 2,468,750 Gudenrath May 3, 1949 2,580,478 Stine Jan. 1, 1952 OTHER REFERENCES Sachanen: Conversion of Petroleum, page 153 (1940); Reinhold Publishing Corp., 330 West 42nd Street, N. Y. 

1. IMPROVED PROCESS FOR THE SEGREGATION OF HYDROCARBONS BOILING IN THE MOTOR FUEL BOILING RANGE FROM A VAPOROUS MIXTURE CONTAINING SAID HYDROCARBONS, LOWER BOILING HYDROCARBONS AND A PREDOMINANTLY LARGE MOL PERCENT OF HYDROGEN WHICH COMPRISES SEGREGATING A VAPOROUS STREAM COMPRISING SAID LOWER BOILING HYDROCARBONS, SOME OF SAID HYDROCARBONS BOILING IN THE MOTOR FUEL BOILING RANGE AND THE HYDROGEN FROM A CONDENSED HYDROCARBON STREAM SUBSTANTIALLY COMPLETELY FREE OF HYDROGEN IN AN INITIAL SEPARATION ZONE, PASSING SAID CONDENSED STREAM TO A STABILIZATION ZONE WHEREIN A SEPARATION IS MADE BETWEEN HYDROCARBONS BOILING IN THE MOTOR FUEL BOILING RANGE AND LOWER BOILING HYDROCARBONS, PASSING SAID HYDROCARBONS BOILING IN THE MOTOR FUEL BOILING RANGE TO A DISTILLATION ZONE WHEREIN A SEPARATION IS MADE BETWEEN LOW BOILING HYDROCARBONS AND HIGH BOILING HYDROCARBONS, PASSING AT LEAST A PORTION OF SAID HIGH BOILING HYDROCARBONS FROM SAID DISTILLATION ZONE INTO THE TOP OF AN ABSORPTION ZONE AS AN ABSORPTION OIL, REMOVING OVERHEAD FROM SAID STABILIZATION ZONE LOWER BOILING HYDROCARBONS, COOLING THE SAME AND PASSING THE COOLED STREAM TO A SECONDARY SEPARATION ZONE, SEGREGATING UNCONDENSED HYDROCARBONS AND PASSING THE SAME TO A LOWER POINT OF SAID ABSORPTION ZONE, PASSING SAID VAPOROUS STREAM FROM SAID INITIAL SEPARATION ZONE INTO AN INTERMEDIATE POINT OF SAID ABSORPTION ZONE, COUNTERCURRENTLY CONTACTING THE UPFLOWING VAPOROUS STREAM WITH SAID DOWNFLOWING ABSORPTION OIL, WHEREBY SAID HYDROCARBONS BOILING IN THE MOTOR FUEL BOILING RANGE ARE ABSORBED IN SAID ABSORPTION OIL, REMOVING HYDROGEN AND HYDROCARBONS BOILING BELOW THE MOTOR FUEL BOILING RANGE OVERHEAD FROM SAID ABSORPTION ZONE AND REMOVING SAID ABSORPTION OIL COMPRISING SAID HIGHER BOILING HYDROCARBONS AND ABSORBED HYDROCARBONS FROM THE BOTTOM OF SAID ABSORPTION ZONE AND PASSING THE SAME TO SAID STABILIZATION ZONE. 